Electric cooktop



FIG. 1 is a perspective view of an electric cooktop appliance showing my ornamental design;

FIG. 2 is a top plan view of the electric cooktop shown in FIG. 1;

FIG. 3 is a right side view of the electric cooktop shown in FIG. 1; and,

FIG. 4 is a left side view of the electric cooktop appliance shown in FIG. 1. 

The ornamental design for an electric cooktop, as shown and described. 